The present invention relates to a radial blower, especially for heaters and air conditioners in motor vehicles, such radial blowers include an impeller wheel, preferably driven by an electric motor, and mounted in a spiral housing, the wall of which approaches in form of a spiral the periphery of the rotating impeller wheel and passes over into a tongue delimiting the outlet of the radial blower at one side thereof. Such radial blowers are known in the art and they have a satisfactory efficiency, but they produce during operation an undesirable noise or a rather disturbing scream. This noise is substantially produced at the aforementioned tongue of the spiral housing. While it has been tried to solve this noise problem by enlarging the radial distance between the periphery of the impeller wheel and the wall of the spiral housing, this solution has the essential disadvantage that it leads to a decisive reduction of the efficiency of the radial blower. Furthermore, the outer dimensions of the spiral housing, especially in the region of the aforementioned tongue are necessarily increased, so that such radial blowers cannot be used in the interior of motor vehicles, in which the available space for such radial blowers is evidently rather limited.